Use the following modules to guide your exploration of the thoracic and abdominal regions of the muscular
system. As you explore the modules, locate the muscles on any charts, models, or specimen available. These
muscles are located on the thorax, abdomen, and back, and serve to protect the cavities they enclose as well
as provide movement.
These muscle groups will have different jobs depending on where they are located. Those muscles on
the chest wall around the ribs play roles in changing the size of the thoracic cavity for inspirations and
expirations. Muscles located along the spine are involved in movement of the back, and muscles lining the
abdomen help to protect the organs underneath while also allowing for movement of the trunk.
The long names of some of these muscles can be daunting, but they are often very descriptive. You can find
origins, insertions, actions, and/or locations of these muscles simply in the names. When reviewing the action
of a muscle, it will be helpful to think about where the muscle is located and where the insertion is. Muscle
physiology requires that a muscle will “pull” instead of “push” during contraction, and the insertion is the
part that will move. Imagine that the muscle is pulling on the bone or tissue it is attached to at the insertion.
Access 3D views and animated muscle actions in Human Anatomy Atlas, which will be especially helpful to
visualize muscle actions. When you select a structure in Atlas, you’ll see options to read the definition and
hear the pronunciation in the content box. When you select a muscle, be sure to select the blue pin icon in
the content box. This will give you the option to view origins and insertions as visible pins on the muscle
(select Attachments), view the blood supply, and/or the nerve supply.
In the modules below, identify the following:
• Muscle location
• Origin(s) and insertion(s)
• Muscle action
• Nerve supply